Means for recovering cemented well casings



Feb. 44, 1941.-

B. H. MILLER MEANS Fon REcovERIvm-r CEMENTED 4WELL cAsINGs l Filed Aug. 16. 1958 A, EG E EN4 K T/ 2 C .0 ,f i, 3 4 m w n mm., Rm am .STEEL c45/ms 5.1/1. MILLER.

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vof the well from another.

Patented Feb. 4, 1941 UNITED STATES MEANS FOR REOOVERING CEMENTD WELL CASINGS Bruno n. Miller, oklahoma city; okla. Application August 16, 1938, Serial No. 225,213

` 1 llaim. The invention .Y relates to casings for oil and water wells and the object of the invention is to provide a method whereby the casing of an oil or other well which has been surrounded by cement or concrete may when desired be removed from the well after the concrete has set.

The process of cementing oil wells 'is well known, the purpose being to seal oif one part At the present time there is no means whereby that portion of the casing which is set in the cement may be removed after the casing has-served its function. In this manner a very great loss of valuable equipment results. Y

In order to eliminate this loss it has been proposed to use sealing material other than cement, thus permitting the entire length of casing to be withdrawn. However, in practice cement is used in nearly all wells and no satisfactory substitute has been found.

The object of my invention is accordingly to provide means for overcoming the tendency of the concrete and the steel to adhere .to one another, so as to permit the casing to be withdrawn fromthe well after it has'served its function. My solution of the problem is to interpose between the steel casing and the concrete'a material of less tensile strength than either.

According to my invention I provide a jacket for the casing which normally adheres thereto but which does not adhere with such a force either to the steel casing or to the concrete that the casing cannot be pulledvout of the well by applying an outside force in a longitudinal direction.

The improved device is in effect a laminated tube or casing, including an inner casing which is the valuable part of the device and which it is .important to recover, and one or more outer layers of relatively inexpensive material, which may be destroyed or-left in the Well when the inner part is drawn out of the well.

The purpose of the present invention is to overcome the tendency of the concrete to stick to the steel casing and to permit said casing to be recovered after it has served its purpose'. I have found that this tendency can be overcome by inn terposing a material of lesser tensile strength than either the steel casing or the concrete between them. Aslong as no longitudinal pressure is exerted on the pipe, the covering will have no function other than to separate the steel casing from the concrete, and `only comes into play when the casing is to be withdrawn from the well. The easiest way to carry out the invention would be the inventive thought involved.

to place the jacket, or other covering, on the casing before it was actually put to use and would have no effect on the casing ifit remained in the hole. The concrete beingv put into the hole in a soft or semi-liquid state would be forced around the` outside of the pipe between the covering and 5 the side of the hole and would therefore adhere to the outside covering rather than to the steel pitre itself.

` metal in which the outer part could be shrunk on the pipe, or any other means used to attach it' thereto with sufilcient adhesive qualities so that it would not sepafateunless force were applied. The euter'jacket could also be made of a heavy coating of paper such as building paper or tarred paper which could be glued to the steel casing, or it could consist vof a rubber jacket which could be stretched over the casing, or even of wax or similar material. In short, it could consist of any material or means forming a separate film or partition between the casing and the cement and in such a way that either the casing could be separated from it. or the casing together with the 0 covering separated from the concrete by the application of pressure. The latter contingency would arise in the case of a' rubber jacket, or any other elastic material, which would stretch when pressure would be applied to the casing and by its stretching separate itself from the lconcrete. The invention will be more readily understood by reference to the accompanying drawing in which is set forth an illustrative embodiment of In the drawing: 40 Fig. 1 is a diagrammatic view of an oil well including a casing embodying the present' invention.

Fig. 2 is a vertical section showing a portion of the jacketed casing embedded in the concrete. Fig. 3 is a horizontal section of the jacketed casing.

Referring to the drawing, the reference numeral I0 denotes generally an oil, gas or'water 50 well which is provided with a casing ll. A portion of the well is cemented at I2. 'Ihe casing is of course made up in sections, the various -lengths of the casing being threaded together.

the principal part of lo tion o! the casing il may be readily removed but prior to the praent invention. the portion surrounded by the cement or concrete had to-be abandoned resulting in tremendous losses, frequently amountingto as much as $5,000.00 per well.

According to my invention the inner steel casing I! or at least that portion which is to. be embedded in concrete is provided with a jacket Il may be oi paper. rubber. a baser metal than'steelormaybeoihardparaiiinwaxor similar material, having relatively high melting points. Grease, fat or material melting under normal conditions met with in an oil well. be avoided. Plastic materials 'such as synthetic resins, or plaster of Paris which will crumble when-pressure is applied in pulling, might also be used.

When such a Jacket I4 is employed the inner above the cement 'or concrete` 2,230,026 casing be withdrawn from the well by the l In. a cemented oil well. a casing having s. rub- 15 ber jacket separating the steel portion from the cement. l

. BRUNO HsLmLER. 

